I had the same issue when trying to add my kwikset 916 dead bolt; it would let me add it however would not let me control it. As many did, I added my z-wave network key to the config file after my initial z-wave set up. However, I found a much better option then manually entering.
If you have already set up your z-wave network and have added zwave: code to the configuration file follow these steps to fix your secure devices:
Step 1: Remove your secure devices from the z-wave network by selecting the node and clicking “remove node” (Follow each devices remove from network instructions).
Step 2: After you have removed the devices from your network. Remove the z-wave code you manually added to any configuration/option file.
Step 3: Go to Configuration>Integrations> Delete the Z-Wave Integration
(Note: This will not remove your existing devices since they are stored on your Z-Wave Stick. However, if you have created custom names for devices you may have to rename them again after.)
Step 4: Go to Supervisor>System>Reboot
Step 5: Create a network key
(There are many ways to generate one however I just changed some of the characters of this example one I found)
0x67, 0x8b, 0x93, 0x5d, 0x84, 0x8b, 0x58, 0x31, 0x06, 0x08, 0xe9, 0xf7, 0xaa, 0x60, 0x9d, 0x5e
(Note: There should not be a z-wave integration after reboot, also your configuration files should be z-wave free at this point)
Step 6: Go to Configuration>Integration>Click “Add Integration”>Add Z-Wave>A dialog box will pop up with 2 text boxes, Path & Network Key
Step 7: For Path Enter: /dev/ttyACM0 For Network Key Enter your network key without parentheses
Example: 0x67, 0x8b, 0x93, 0x5d, 0x84, 0x8b, 0x58, 0x31, 0x06, 0x08, 0xe9, 0xf7, 0xaa, 0x60, 0x9d, 0x5e
Step 8: Start the Z-Wave network and add your secure devices that you removed using Add Node Secure.
Happy Holidays.